title: Disruption of Myc-Max heterodimerization with improved cell-penetrating analogs of the small molecule 10074-G5.
abstract: The c-Myc (Myc) oncoprotein is a high-value therapeutic target given that it is deregulated in multiple types of cancer. However, potent small molecule inhibitors of Myc have been difficult to identify, particularly those whose mechanism relies on blocking the association between Myc and its obligate heterodimerization partner, Max. We have recently reported a structure-activity relationship study of one such small molecule, 10074-G5, and generated an analog, JY-3-094, with significantly improved ability to prevent or disrupt the association between recombinant Myc and Max proteins. However, JY-3094 penetrates cells poorly. Here, we show that esterification of a critical para-carboxylic acid function of JY-3-094 by various blocking groups significantly improves cellular uptake although it impairs the ability to disrupt Myc-Max association in vitro. These pro-drugs are highly concentrated within cells where JY-3-094 is then generated by the action of esterases. However, the pro-drugs are also variably susceptible to extracellular esterases, which can deplete extracellular reservoirs. Furthermore, while JY-3-094 is retained by cells for long periods of time, much of it is compartmentalized within the cytoplasm in a form that appears to be less available to interact with Myc. Our results suggest that persistently high extracellular levels of pro-drug, without excessive susceptibility to extracellular esterases, are critical to establishing and maintaining intracellular levels of JY-3-094 that are sufficient to provide for long-term inhibition of Myc-Max association. Analogs of JY-3-094 appear to represent promising small molecule Myc inhibitors that warrant further optimization.
authors.affiliation: Section of Hematology/Oncology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA.
authors.forename: Huabo
authors.initials: H
authors.lastname: Wang
authors.forename: Jay
authors.initials: J
authors.lastname: Chauhan
authors.forename: Angela
authors.initials: A
authors.lastname: Hu
authors.forename: Kelsey
authors.initials: K
authors.lastname: Pendleton
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: Yap
authors.forename: Philip E
authors.initials: PE
authors.lastname: Sabato
authors.forename: Jace W
authors.initials: JW
authors.lastname: Jones
authors.forename: Mariarita
authors.initials: M
authors.lastname: Perri
authors.forename: Jianshi
authors.initials: J
authors.lastname: Yu
authors.forename: Erika
authors.initials: E
authors.lastname: Cione
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Kane
authors.forename: Steven
authors.initials: S
authors.lastname: Fletcher
authors.forename: Edward V
authors.initials: EV
authors.lastname: Prochownik
mesh_terms: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D057809:HEK293 Cells; D006801:Humans; D013058:Mass Spectrometry; D010069:Oxadiazoles / Q000737:chemistry* / Q000493:pharmacokinetics*; D011485:Protein Binding; D055503:Protein Multimerization; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: C534883:10074-G5; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C499330:MAX protein, human; C489427:MYC protein, human; D010069:Oxadiazoles; D016271:Proto-Oncogene Proteins c-myc